1. Technical Field
The present disclosure relates to a display device, a driving method thereof, and an electronic apparatus including the display device.
2. Description of the Related Art
Recent years have seen a growing demand for display devices for use in, for example, mobile devices such as mobile phones and electronic paper. In a display device, a single pixel includes a plurality of sub-pixels, each of which emits light of a different color. The single pixel displays various colors by switching on and off display of the sub-pixels. Such display devices have been improved year after year in display properties such as resolution and luminance. However, an increase in the resolution reduces an aperture ratio, and thus increases necessity for increase in luminance of a backlight to achieve high luminance, causing a problem of increase in power consumption of the backlight. There is a technique (such as Japanese Patent Application Laid-open Publication No. 2012-108518) to improve this in which a white sub-pixel as a fourth sub-pixel is added to the conventional sub-pixels of red, green, and blue. This technique reduces the current value of the backlight by an increase in the luminance with the white sub-pixel, and thereby reduces the power consumption. The white sub-pixel increases the luminance when the current value of the backlight is not reduced. Thus, there is a technique (such as Japanese Patent Application Laid-open Publication No. 2012-22217 ([JP-A-2012-22217]) that uses this to improve visibility under outside light of outdoors.
The technique of JP-A-2012-22217 changes an extension coefficient for extending an input signal according to brightness of the input signal. For example, the extension coefficient is set larger on the side where the brightness is low, that is, on the low-gradation side, and is set smaller on the side where the brightness is high, that is, on the high-gradation side. This results in increasing the luminance on the low-gradation side, thus improving the visibility of the display device in outdoors. However, the technique of JP-A-2012-22217 applies an always constant value of the extension coefficient to saturation, and thus can cause a reduction (deterioration) in display quality, such as gradation collapse and change in color, on the high-saturation side.
For the foregoing reasons, there is a need for suppressing a reduction in visibility of a display device while reducing deterioration in display quality of the display device, under outside light.